The present invention relates to alarm systems for aircraft, and particularly to such systems which actuate an alarm when the ground-closure rate of the aircraft is found to be excessive.
A number of excessive ground-closure rate alarm systems have been proposed for use in aircraft in order to actuate an alarm, and thereby to alert the pilot, if the ground-closure rate (sometimes called descent rate) is found to be excessive such that there is a danger of collision with the ground. Examples of such systems are described in the U.S. Pat. Nos. 2,809,340; 2,930,035; 3,715,718; 3,925,751; 3,934,222; 3,936,796; 3,958,218-9, 3,988,713; 4,060,793; and 4,293,840. These systems usually include altitude measuring means for measuring the altitude of the aircraft, means for computing therefrom the ground-closure rate, and alarm means for producing an alarm when the computed ground-closure rate is excessive for the particular altitude. Most of these known systems have been designed for use by fixed-wing aircraft.
An object of the present invention is to produce a novel excessive ground-closure rate alarm system having a number of advantages over the known systems, particularly when used by helicopters.